no pv entries: increase vm.pmap.shpgperproc

[peter]

> In response to "peter" <peter at topcomtech.com.cn>:
> > Hi,
> > My freebsd box runs the apache httpd2.0 server, postgresql8.1server,
> > Recently, I got the below info in /var/crash.
> > “Dump header from device /dev/da0s1b
> >   Architecture: i386
> >   Architecture Version: 2
> >   Dump Length: 1073127424B (1023 MB)
> >   Blocksize: 512
> >   Dumptime: Wed Jan 17 16:39:08 2007
> >   Hostname: myhost.mydomain.com
> >   Magic: FreeBSD Kernel Dump
> >   Version String: FreeBSD 6.0-RELEASE #0: Tue Apr 25 15:07:33 CST 2006
> >     peter at myhost.mydomain.com:/usr/src/sys/i386/compile/MYKNL
> >   Panic String: no pv entries: increase vm.pmap.shpgperproc
> >   Dump Parity: 2383301964
> >   Bounds: 49
> >   Dump Status: good”
> > I had searched in google, but I didn’t know how to do.
> 
> You _should_ be able to raise the vm.pmap.shpgperproc sysctl to prevent
> the problem -- but there doesn't seem to be any such sysctl.  I'm not sure
> what's going on here, but it seems to me that a PR is in order.

I  had ever added the line "kern.vm.pmap.shpgperproc=4096" to /boot/loader.conf ,
but it seems to be ineffective.

> Failing that, you could set the following in your kernel config:
> options PMAP_SHPGPERPROC=250
> and rebuild/reinstall your kernel. 
>
> The default value is 200, so I expect 250 will be enough of a bump to
> fix the problem.  If it's not, raise it a little higher and try again.
> I don't know of any way to tell exactly what this value should be other
> than trial and error.  I've seen warnings that raising this value too
> high can result in an unbootable kernel, so take care to understand how
> to recover from the installation of an unbootable kernel.

How to know the default value? 
The website on the box has about 22000  visits every day, so i think the physical 
memory size maybe small. 
I configured httpd.conf like this:
....
KeepAlive Off
....
<IfModule prefork.c>
StartServers         8
MinSpareServers      3
MaxSpareServers      5
ServerLimit    170
MaxClients         160
MaxRequestsPerChild 300
</IfModule>
.....

Thanks very much Bill

peter



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